Every time when I make a tight binding exercise the convention of the sign of the hopping t changes. Sometimes it is defined as -t and sometimes as +t, this is fine, but now I am remaking the minitest 2 (from this year). The hopping in the figure is defined as positive and “t > 0” is stated in the description of exercise 2 of the minitest. But in the answer still the minus comes in in front of the t. Can you explain the convention, or is it not an important matter?
Thank you in advance for your response.